The invention concerns an over temperature shut-off or fire-protection valve with a sealing-spring for automatically shutting-off conduits, especially gas conduits. Such valves are used in piping e.g. upstream of gas-fittings, gas equipment and gas meters etc. Their purpose is, in cases of an excessively high temperature condition such as fire, to cut-off gas supplies before the temperatures in the immediate vicinity of the previously named gas equipments becomes excessive.
Presently, primarily valves are used whose closure bodies are conical or spherical.
A valve is known, as given in EP-OS 118 52, by which a cone is held either in the closed position on reaching a limiting temperature or in the open position by a spring on one side and an alloy with thermal shape-memory properties on the other side, whereby the spring is formed such that after closing, self-opening is not possible.
With this solution, it is a disadvantage that if the spring loses its strength at very high temperatures, safe sealing is no longer guaranteed.
EP-OS 118 52 also describes a valve whose closure body is a sphere. With this solution, a guide rod which penetrates a valve cap is connected to a sphere with a fusible body, which is held tightly to the cap by a compression spring. As soon as the fusible body melts, the guide rod is drawn out of the cap such that the sphere can move abruptly, due to the compression spring, in the closure direction.
Also with this solution, it is a disadvantage that if the spring loses its strength due to very high temperatures, safe sealing is no longer guaranteed. In addition, this solution has the shortcoming that to achieve the required gas-tightness, the sphere and its seating must fit exactly with respect to roundness and surface quality. This leads on the one hand to very high production costs and on the other hand to the fact that the gas-tightness of this combination is not reproducible. With renewed application, which is generally done by rotating the sphere, a completely different leakage rate is achieved particularly if the roundness of both components is not perfect. For this reason gas-tightness tests also performed during production do not bring the desired success, as only very high leakage rates can be guaranteed.
The present state-of-art solutions for usage with through-way valves, e.g. as described in DE-OS 39 16 100, by which the closure body is moved vertically to the flow direction, are especially unsatisfactory. This results in components or profiles protruding from the piping profile. When using a sphere, it is additionally necessary to machine together both sides of the sphere skin sealing surfaces together which leads to very high production costs.
The resulting high price of these valves has previously prevented their otherwise desired general usage.
The present invention takes as its basis the problem of developing a valve of the named type that guarantees a reproducible tight seal. Even when the elasticity loses strength at very high temperatures, it is to be ensured that the valve itself remains closed whether due to shock or vibration. Additionally the valve is to be designed such that there are no components which protrude from the piping profile. Thus the valve according to the invention can be fitted directly into piping systems. Likewise normal stopcocks should be able to be operated without difficulty. Manufacturing costs are additionally to be held as low as possible.
According to the invention, the problem is solved by the named characteristics in the marked part of the Patent claim 1. The resulting advantage of the invention is especially that it is ensured that the valve maintains its gas-tight closure position after closing even in the event of failure of closure springs due to high temperature and by shock, and that a reproducible gas-tight seal is guaranteed. Additonally the valve is designed such that no components protrude from the piping profile and therefore the valve, according to the present invention, can be fitted directly into piping systems and normal stopcocks can be operated without difficulty.
Advantageous arrangements are given in Patent claims 2 to 9. The present invention provide a simple design through which production costs can be kept very low. Realization examples of the invention are given in drawings and given in detail as follows: